Off-highway implements, such as front-end loaders and the like, are typically provided with a loader mechanism at one end thereof. A conventional loader mechanism includes a working tool such as a bucket or the like pivotally connected to a frame of the implement by longitudinally extending loader arms. A series of hydraulic actuators, usually in the form of double-acting hydraulic cylinders, are connected to a hydraulic system of the implement for effecting various loader functions. Hydraulic actuators are used to elevationally position the bucket or tool by raising and lowering the loader arms. Hydraulic actuators are likewise used to control the roll or pivotal movement of the bucket relative to the loader arms. Many loader mechanisms further incorporate a device such as a clam shell bucket which utilizes hydraulic actuators to effect articulated movement of the clam shell bucket to effect a "grab" function.
Control over the various loader functions or work operations is conventionally achieved through manipulation of various control levers. Each control lever is connected to one or more control valves which, in turn, regulates hydraulic fluid flow between a pressurized hydraulic source on the implement and each of the actuators.
During operation of the implement, the loader mechanism can perform a single function, but usually at least two loader functions are effected simultaneously relative to each other. That is, while the loader arms are being elevationally adjusted, the pivotal position or roll of the bucket may likewise be adjusted. When the loader is equipped with a clam shell bucket, all three loader functions may be effected simultaneously to economize on operational time for the loader. As will be appreciated, controlling the implements direction and speed simultaneously with the raising, lowering, tilting, and articulating movements of the bucket of the loader mechanism through movement of a multiplicity of control levers can become a cumbersome task for anyone to perform successfully.
Thus, there is a need and a desire for a control system including a single control lever capable of effecting regulation of various loader functions either independently of one another or in unison with one another or, in any combination desired by the operator.